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Unable to create RFTYM TTY: address already in use

I am listening to a bluetooth connection on my server:

rfcomm listen rfcomm1 1

Then I connect to my Bluetooth client, and the following message appears:

 Connection from XX:XX:XX:XX:XX:XX to /dev/rfcomm1 Press CTRL-C for hangup

This means that everything is in order ...

Then I end my connection by doing Ctrl + C on the server or client.

After that, I again:

 rfcomm listen rfcomm1 1

But this time, when I connect the client, I get this message:

 Can't create RFCOMM TTY: Address already in use

So, I go and check which connections are open:

 rfcomm -a

And I see that the connection appears as closed, but should not appear after disconnection ...

 rfcomm1: XX:XX:XX:XX:XX:XX -> XX:XX:XX:XX:XX:XX channel 1 closed [reuse-dlc release-on-hup ]

The strangest thing is that sometimes the disconnection is successful, and I can connect again without any problems.

EDIT

I realized that when the device continues to connect for about 10 seconds or more, disconnection is successful. But when this time is shorter (quick connect / disconnect), a problem arises.

And if during a failure occurs:

 dmesg

This is printed:

 [11800.001527] Bluetooth: TIOCGSERIAL is not supported [11800.033063] Bluetooth: TIOCGSERIAL is not supported [11926.708438] Bluetooth: TIOCGSERIAL is not supported [11934.918197] Bluetooth: TIOCGSERIAL is not supported [11934.926194] Bluetooth: TIOCGSERIAL is not supported [11934.926284] ------------[ cut here ]------------ [11934.926297] WARNING: CPU: 1 PID: 2316 at /build/linux-Pcn0xK/linux-4.4.0/drivers/tty/tty_port.c:143 tty_port_destructor+0x7a/0x80() [11934.926300] Modules linked in: minidriver(OE) nls_utf8 isofs rfcomm bnep arc4 ath5k snd_hda_codec_realtek uvcvideo ath mac80211 snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_intel videobuf2_vmalloc snd_hda_codec samsung_laptop videobuf2_memops snd_hda_core btusb videobuf2_v4l2 btrtl snd_hwdep videobuf2_core coretemp btbcm cfg80211 snd_pcm v4l2_common btintel snd_seq_midi joydev videodev bluetooth snd_seq_midi_event serio_raw media snd_rawmidi input_leds snd_seq snd_seq_device snd_timer snd soundcore shpchp lpc_ich mac_hid binfmt_misc parport_pc ppdev lp parport autofs4 hid_logitech ff_memless uas usb_storage hid_generic usbhid hid amdkfd amd_iommu_v2 radeon psmouse pata_acpi i2c_algo_bit ttm sky2 drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops video fjes drm [last unloaded: minidriver] [11934.926401] CPU: 1 PID: 2316 Comm: kworker/1:1 Tainted: GW OE 4.4.0-97-generic #120-Ubuntu [11934.926404] Hardware name: SAMSUNG ELECTRONICS CO., LTD. R520/R522/R620 /R520/R522/R620 , BIOS 05LL.M025.20090916.Jay 09/16/20 [11934.926410] Workqueue: events release_one_tty [11934.926413] 0000000000000286 c977cef9c84bca31 ffff88012ea3fd48 ffffffff813fabe3 [11934.926419] 0000000000000000 ffffffff81d386c0 ffff88012ea3fd80 ffffffff810812e2 [11934.926425] ffff8800b5153800 ffff8800b67f6400 ffff8800b67f6400 ffffffffc06dc840 [11934.926430] Call Trace: [11934.926438] [<ffffffff813fabe3>] dump_stack+0x63/0x90 [11934.926445] [<ffffffff810812e2>] warn_slowpath_common+0x82/0xc0 [11934.926450] [<ffffffff8108142a>] warn_slowpath_null+0x1a/0x20 [11934.926455] [<ffffffff8150357a>] tty_port_destructor+0x7a/0x80 [11934.926460] [<ffffffff81503ce8>] tty_port_put+0x28/0x30 [11934.926471] [<ffffffffc06d5fa8>] rfcomm_tty_cleanup+0x68/0x70 [rfcomm] [11934.926475] [<ffffffff814f91fb>] release_one_tty+0x3b/0xc0 [11934.926481] [<ffffffff8109a635>] process_one_work+0x165/0x480 [11934.926486] [<ffffffff8109a99b>] worker_thread+0x4b/0x4c0 [11934.926491] [<ffffffff8109a950>] ? process_one_work+0x480/0x480 [11934.926496] [<ffffffff810a0c75>] kthread+0xe5/0x100 [11934.926500] [<ffffffff810a0b90>] ? kthread_create_on_node+0x1e0/0x1e0 [11934.926507] [<ffffffff81843b8f>] ret_from_fork+0x3f/0x70 [11934.926511] [<ffffffff810a0b90>] ? kthread_create_on_node+0x1e0/0x1e0 [11934.926515] ---[ end trace a33c33d1fdbe410d ]--- [11936.001325] Bluetooth: TIOCGSERIAL is not supported [11936.033194] Bluetooth: TIOCGSERIAL is not supported (OE) nls_utf8 isofs rfcomm bnep arc4 ath5k snd_hda_codec_realtek uvcvideo ath mac80211 snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_intel videobuf2_vmalloc snd_hda_codec samsung_laptop videobuf2_memops snd_hda_core btusb videobuf2_v4l2 btrtl snd_hwdep videobuf2_core coretemp btbcm cfg80211 snd_pcm v4l2_common btintel snd_seq_midi joydev videodev bluetooth snd_seq_midi_event serio_raw media snd_rawmidi input_leds snd_seq [11800.001527] Bluetooth: TIOCGSERIAL is not supported [11800.033063] Bluetooth: TIOCGSERIAL is not supported [11926.708438] Bluetooth: TIOCGSERIAL is not supported [11934.918197] Bluetooth: TIOCGSERIAL is not supported [11934.926194] Bluetooth: TIOCGSERIAL is not supported [11934.926284] ------------[ cut here ]------------ [11934.926297] WARNING: CPU: 1 PID: 2316 at /build/linux-Pcn0xK/linux-4.4.0/drivers/tty/tty_port.c:143 tty_port_destructor+0x7a/0x80() [11934.926300] Modules linked in: minidriver(OE) nls_utf8 isofs rfcomm bnep arc4 ath5k snd_hda_codec_realtek uvcvideo ath mac80211 snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_intel videobuf2_vmalloc snd_hda_codec samsung_laptop videobuf2_memops snd_hda_core btusb videobuf2_v4l2 btrtl snd_hwdep videobuf2_core coretemp btbcm cfg80211 snd_pcm v4l2_common btintel snd_seq_midi joydev videodev bluetooth snd_seq_midi_event serio_raw media snd_rawmidi input_leds snd_seq snd_seq_device snd_timer snd soundcore shpchp lpc_ich mac_hid binfmt_misc parport_pc ppdev lp parport autofs4 hid_logitech ff_memless uas usb_storage hid_generic usbhid hid amdkfd amd_iommu_v2 radeon psmouse pata_acpi i2c_algo_bit ttm sky2 drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops video fjes drm [last unloaded: minidriver] [11934.926401] CPU: 1 PID: 2316 Comm: kworker/1:1 Tainted: GW OE 4.4.0-97-generic #120-Ubuntu [11934.926404] Hardware name: SAMSUNG ELECTRONICS CO., LTD. R520/R522/R620 /R520/R522/R620 , BIOS 05LL.M025.20090916.Jay 09/16/20 [11934.926410] Workqueue: events release_one_tty [11934.926413] 0000000000000286 c977cef9c84bca31 ffff88012ea3fd48 ffffffff813fabe3 [11934.926419] 0000000000000000 ffffffff81d386c0 ffff88012ea3fd80 ffffffff810812e2 [11934.926425] ffff8800b5153800 ffff8800b67f6400 ffff8800b67f6400 ffffffffc06dc840 [11934.926430] Call Trace: [11934.926438] [<ffffffff813fabe3>] dump_stack+0x63/0x90 [11934.926445] [<ffffffff810812e2>] warn_slowpath_common+0x82/0xc0 [11934.926450] [<ffffffff8108142a>] warn_slowpath_null+0x1a/0x20 [11934.926455] [<ffffffff8150357a>] tty_port_destructor+0x7a/0x80 [11934.926460] [<ffffffff81503ce8>] tty_port_put+0x28/0x30 [11934.926471] [<ffffffffc06d5fa8>] rfcomm_tty_cleanup+0x68/0x70 [rfcomm] [11934.926475] [<ffffffff814f91fb>] release_one_tty+0x3b/0xc0 [11934.926481] [<ffffffff8109a635>] process_one_work+0x165/0x480 [11934.926486] [<ffffffff8109a99b>] worker_thread+0x4b/0x4c0 [11934.926491] [<ffffffff8109a950>] ? process_one_work+0x480/0x480 [11934.926496] [<ffffffff810a0c75>] kthread+0xe5/0x100 [11934.926500] [<ffffffff810a0b90>] ? kthread_create_on_node+0x1e0/0x1e0 [11934.926507] [<ffffffff81843b8f>] ret_from_fork+0x3f/0x70 [11934.926511] [<ffffffff810a0b90>] ? kthread_create_on_node+0x1e0/0x1e0 [11934.926515] ---[ end trace a33c33d1fdbe410d ]--- [11936.001325] Bluetooth: TIOCGSERIAL is not supported [11936.033194] Bluetooth: TIOCGSERIAL is not supported parport_pc ppdev lp parport autofs4 hid_logitech ff_memless uas usb_storage hid_generic usbhid hid amdkfd amd_iommu_v2 radeon psmouse pata_acpi i2c_algo_bit ttm sky2 drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops video fjes drm [last unloaded: minidriver] [11800.001527] Bluetooth: TIOCGSERIAL is not supported [11800.033063] Bluetooth: TIOCGSERIAL is not supported [11926.708438] Bluetooth: TIOCGSERIAL is not supported [11934.918197] Bluetooth: TIOCGSERIAL is not supported [11934.926194] Bluetooth: TIOCGSERIAL is not supported [11934.926284] ------------[ cut here ]------------ [11934.926297] WARNING: CPU: 1 PID: 2316 at /build/linux-Pcn0xK/linux-4.4.0/drivers/tty/tty_port.c:143 tty_port_destructor+0x7a/0x80() [11934.926300] Modules linked in: minidriver(OE) nls_utf8 isofs rfcomm bnep arc4 ath5k snd_hda_codec_realtek uvcvideo ath mac80211 snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_intel videobuf2_vmalloc snd_hda_codec samsung_laptop videobuf2_memops snd_hda_core btusb videobuf2_v4l2 btrtl snd_hwdep videobuf2_core coretemp btbcm cfg80211 snd_pcm v4l2_common btintel snd_seq_midi joydev videodev bluetooth snd_seq_midi_event serio_raw media snd_rawmidi input_leds snd_seq snd_seq_device snd_timer snd soundcore shpchp lpc_ich mac_hid binfmt_misc parport_pc ppdev lp parport autofs4 hid_logitech ff_memless uas usb_storage hid_generic usbhid hid amdkfd amd_iommu_v2 radeon psmouse pata_acpi i2c_algo_bit ttm sky2 drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops video fjes drm [last unloaded: minidriver] [11934.926401] CPU: 1 PID: 2316 Comm: kworker/1:1 Tainted: GW OE 4.4.0-97-generic #120-Ubuntu [11934.926404] Hardware name: SAMSUNG ELECTRONICS CO., LTD. R520/R522/R620 /R520/R522/R620 , BIOS 05LL.M025.20090916.Jay 09/16/20 [11934.926410] Workqueue: events release_one_tty [11934.926413] 0000000000000286 c977cef9c84bca31 ffff88012ea3fd48 ffffffff813fabe3 [11934.926419] 0000000000000000 ffffffff81d386c0 ffff88012ea3fd80 ffffffff810812e2 [11934.926425] ffff8800b5153800 ffff8800b67f6400 ffff8800b67f6400 ffffffffc06dc840 [11934.926430] Call Trace: [11934.926438] [<ffffffff813fabe3>] dump_stack+0x63/0x90 [11934.926445] [<ffffffff810812e2>] warn_slowpath_common+0x82/0xc0 [11934.926450] [<ffffffff8108142a>] warn_slowpath_null+0x1a/0x20 [11934.926455] [<ffffffff8150357a>] tty_port_destructor+0x7a/0x80 [11934.926460] [<ffffffff81503ce8>] tty_port_put+0x28/0x30 [11934.926471] [<ffffffffc06d5fa8>] rfcomm_tty_cleanup+0x68/0x70 [rfcomm] [11934.926475] [<ffffffff814f91fb>] release_one_tty+0x3b/0xc0 [11934.926481] [<ffffffff8109a635>] process_one_work+0x165/0x480 [11934.926486] [<ffffffff8109a99b>] worker_thread+0x4b/0x4c0 [11934.926491] [<ffffffff8109a950>] ? process_one_work+0x480/0x480 [11934.926496] [<ffffffff810a0c75>] kthread+0xe5/0x100 [11934.926500] [<ffffffff810a0b90>] ? kthread_create_on_node+0x1e0/0x1e0 [11934.926507] [<ffffffff81843b8f>] ret_from_fork+0x3f/0x70 [11934.926511] [<ffffffff810a0b90>] ? kthread_create_on_node+0x1e0/0x1e0 [11934.926515] ---[ end trace a33c33d1fdbe410d ]--- [11936.001325] Bluetooth: TIOCGSERIAL is not supported [11936.033194] Bluetooth: TIOCGSERIAL is not supported

When everything is working fine (10 seconds or more), only these messages are displayed:

 [11936.001325] Bluetooth: TIOCGSERIAL is not supported [11936.033194] Bluetooth: TIOCGSERIAL is not supported [11936.001325] Bluetooth: TIOCGSERIAL is not supported [11936.033194] Bluetooth: TIOCGSERIAL is not supported
+8
linux tty bluetooth rfcomm bluez
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3 answers

DECISION

The problem was the package that was installed on Ubuntu, which interfered with the normal release of the device.

Just do:

 apt-get remove --purge modemmanager
+3
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Have you tried using the release?

sudo rfcomm release 0

Or, alternatively, by directly adding your device to /etc/bluetooth/rfcomm , and then tying it up, and then try the release after you are done.

sudo rfcomm bind 0

+4
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Given that there is no problem, if you wait 10 seconds before disconnecting, I think that we have a solid lead: the RFCOMM specification ( https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=263754 ) defines 10 seconds as the minimum timeout for ACK data ("Confirmation timer (T1)") and control channel responses ("Response timer for multiplexer control channel (T2)"). Most likely, you have data without ACKed on the control channel from your client (it does not seem like you sent the data). Although I did not expect this to cause problems on shutdown, it is likely that a problem in the BlueZ stack causes problems when trying to release TTY while waiting for this ACK.

  • Did you try to send data to the channel? If the control channel really goes without ACK'd, it would be surprising if you could exchange data.

  • Have you tried using another device as your RFCOMM client? Perhaps the problem in the client-side stack is not ACKing control signals.

I have not worked much with the BlueZ stack, so I cannot provide accurate code changes, but I hope this is enough to formulate a workflow (for example, if you can keep track of the timer waiting for this ACK, maybe you can kill it).

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